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  1. Triuridaceae Gardner

    1. This family is accepted.

[NTK]

Maas, P.J.M. & Maas-van de Kamer, H. (2009). Neotropical Triuridaceae.

Morphology
Description

Myco-heterotrophic ("saprophytic"), small herbs, lacking chlorophyll; rhizome mostly well-developed, creeping, provided with many scale-like leaves; roots filiform , very rarely coral-shaped, with or without root -hairs. Stems mostly unbranched, white, yellow, purple, or red. Leaves alternate , sessile , simple , entire , small and scale-like. Inflorescence a terminal , bracteate, few- to many-flowered raceme . Flowers unisexual (then plants monoecious or dioecious ) or bisexual , actinomorphic , white, yellow, purplish, or red; tepals 3-6, basally connate , often soon reflexed , inner side often densely papillate, apex sometimes provided with dense tufts of hairs ( bearded ) or long-tailed; bisexual flowers: 2-6 free stamens and many free ovaries; staminate flowers: 2-6 mostly epitepalous stamens (except for Triuris Miers), free or implanted on a central androphore ; anthers dithecic or rarely monothecic (Triuridopsis H.Maas & Maas), 2-4-locular, longitudinally or transversely extrorsely dehiscent ; pistillate flowers: 10-many free carpels, implanted on the receptacle ; ovary 1-locular with 1 basal , anatropous ovule , apical part of ovary often papillate; style 1, lateral , rarely terminal (Triuris), about as long as the ovary or far exceeding it, stigmatic zone papillate, penicillate, or glabrous . Fruit consisting of achenes or 1-seeded follicles. Seed 1, globose to obovoid, small.

Distribution
Distribution in the Neotropics

Family: from Guatemala in the North to S Brazil and N Paraguay in the South, absent in the West Indian Islands.

Genera:

  • Lacandonia E.Martínez & Ramos - Mexico (Chiapas).
  • Peltophyllum Gardn. - SE Brazil and adjacent Argentina and Paraguay, and Guyana.
  • Sciaphila Blume - From Guatemala in the North to S Brazil and N Paraguay in the South.  
  • Soridium Miers - From Guatemala in the North to Brazil (Mato Grosso) in the South.
  • Triuridopsis - Peru (Loreto).
  • Triuris - From Guatemala in the North to S Brazil and N Paraguay in the South.
Diagnostic
Distinguishing characters (always present)
  • Myco-heterotrophic herbs, lacking chlorophyll.
  • Leaves alternate, scale-like.
  • Inflorescence a raceme.
  • Tepals basally connate.
  • Gynoecium apocarpous and composed of 10-many free ovaries.
  • Fruit consisting of achenes or follicles.
Other important characters
  • Flowers often unisexual.
  • Inner side of tepals often densely papillate.
  • Apex sometimes provided with dense tufts of hairs (bearded) or long-tailed.
  • Stamens free or on a central androphore.
Key differences from similar families
  • From the other 2 myco-heterotrophic monocotyledonous families Burmanniacae and Thismiaceae Triuridaceae can be easily distinguished by its flowers which have many free carpels.
Useful tips for generic identification

Key to genera of Neotropical Triuridaceae

1. Flowers bisexual; stamens placed in the center of the flower within the carpels ... Lacandonia
1. Flowers unisexual or rarely bisexual, but than the stamens always placed outside and around the carpels ... 2

2. Plants monoecious; flowers unisexual (2 species of Sciaphila bisexual); number of tepals 4, 6, or 8; number of stamens 2, 3, 4, or 6; tepals bearded; style basal; fruit dehiscent or indehiscent... 3
2. Plants dioecious; flowers unisexual; number of tepals 3 or 6; number of stamens 3 or 6; tepals long-tailed; style apical; fruit indehiscent... 4 

3. Staminate flowers with 2 stamens and 4 tepals; fruit an indehiscent achene... Soridium
3. (Staminate) flowers with 3 or 6 stamens, and 4 or 6 tepals; fruit a dehiscent follicle... Sciaphila

4. Staminate flowers with anthers sessile on a conical androphore... Triuris
4. Staminate flowers without conical androphore... 5 

5. Staminate flowers with 3 tepals, 6 filamented, monothecal anthers and a sterile projection in the centre of the flower... Triuridopsis
5. Staminate flowers with 6 tepals, 3 sessile, dithecal anthers and no sterile projection in the centre of the flower... Peltophyllum                                                                                                                                  

Notable genera and distinguishing features
  • Lacandonia is made unique in the Plant Kingdom by its stamens which are placed in the centre of the flower, surrounded by the apocarpous carpels.
  • One of the species of Sciaphila, S. purpurea Benth., can reach a height of almost 1.5 m! It is often found growing on termites' nests.
  • Triuris is quite spectacular in having 3 long-tailed tepals and in having male flowers with sessile stamens implanted in a fleshy and conical androphore.
General Description
Number of genera

6 genera:

  • Lacandonia (1 sp.)
  • Peltophyllum (2 spp.)
  • Sciaphila (8 spp.)  
  • Soridium (1 sp.)
  • Triuridopsis (1 sp.)
  • Triuris (3 spp.)
Status
  • All genera are native.
General notes
  • Most myco-heterotrophic plant groups in the Neotropics (incl. Burmanniaceae and Thismiaceae) are poorly known and much additional field work needs to be conducted. Peltophyllum caudatum (Poulsen) R.Schmid & M.D.Turner and Triuridopsis peruviana H.Maas & Maas are both only known from 1 collection!
  • Rudall (2003) suggest that flowers of Triuridaceae may equally be interpreted as pseudanthia, i.e. modified and highly reduced partial inflorescences.
Notes on delimitation
  • Most recent research places this family in the order of Pandanales (Maas & Weustenfeld, 1998, p. 487).
  • The genus Lacandonia E.Martínez & Ramos was previously recognised in a family of its own - Lacandoniaceae.
Literature
Important literature

Maas, P.J.M. and T. Rübsamen. 1986. Triuridaceae. Flora Neotropica Monograph 40: 1-55.

Maas-van de Kamer, H. & P.J.M. Maas. 1994. Triuridopsis,  a new monotypic genus in Triuridaceae. Pl. Syst. Evol. 192: 257-262.

Maas-van de Kamer, H. & T. Weustenfeld. 1998. Triuridaceae. In: K. K. Kubitzki  (ed.), The families and genera of vascular plants 3: 452-458.

Martínez, E. & C.H. Ramos. 1989. Lacandoniaceae (Triuridales): Una nueva familia de Mexico. Ann. Missouri Bot. Gard. 76: 128-135.

Rudall, P.J. 2003. Monocot pseudanthia revisited: Floral structure of the mycoheterotrophic family Triuridaceae. Int. J. Pl. Sci. 164 (5 Suppl.): S307-S320.

[FWTA]

Triuridaceae, F.N. Hepper. Flora of West Tropical Africa 3:1. 1968

Habit
Leafless saprophiytic herbs with simple or subsimple stems furnished with a few pale scales
Flowers
Flowers very small, racemose or subcorymbose, with decurved bracteate pedicels, actinomorphic, monoecious, dioecious or rarely polygamous Female flowers rarely with staminodes Male flowers: stamens 2-6, sometimes only half of them fertile; anthers free or immersed in the mass of the receptacle, 2-locular, dehiscing mostly transversely; connective sometimes produced into long subulate appendages
Perianth
Perianth-segments 3-8, 1-seriate, valvate, sometimes appendaged at the apex, at length reflexed
Male
Male flowers: stamens 2-6, sometimes only half of them fertile; anthers free or immersed in the mass of the receptacle, 2-locular, dehiscing mostly transversely; connective sometimes produced into long subulate appendages
Female
Female flowers rarely with staminodes
Gynoecium
Carpels several, free, 1-locular; style terminal to almost basal; ovule solitary, basal
Fruits
Fruits crowded, opening by a slit
Seeds
Seed erect, with a fleshy white oily undifferentiated nucleus
[FTEA]

Triuridaceae, K. Vollesen. Flora of Tropical East Africa. 1985

Habit
Saprophytic annual or perennial herbs
Leaves
Leaves alternate, reduced to scales
Flowers
Flowers unisexual, sometimes on separate plants, or, more rarely, hermaphrodite, in racemes or contracted raceme-like panicles Female flowers with numerous free carpels; style terminal or ± gynobasic; ovule erect, anatropous Male flowers with (2-)3-6 stamens, rarely with 3 stamens and 3 staminodes; anthers sessile or with short filaments, with 2 or 4 thecae opening by transverse slits; pollen globose, smooth, without apertures
Perianth
Perianth 3-6(-10)-partite, petaloid
Male
Male flowers with (2-)3-6 stamens, rarely with 3 stamens and 3 staminodes; anthers sessile or with short filaments, with 2 or 4 thecae opening by transverse slits; pollen globose, smooth, without apertures
Female
Female flowers with numerous free carpels; style terminal or ± gynobasic; ovule erect, anatropous
Fruits
Monocarps with a single seed, dehiscent or not
Seeds
Seeds ellipsoid, with copious endosperm

Images

Accepted Genera

Other Data

Triuridaceae Gardner appears in other Kew resources:

Bibliography

First published in Trans. Linn. Soc. London 19: 160. 1843 [4 Aug 1843] (1843)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385

Sources

Flora of Tropical East Africa
Flora of Tropical East Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Flora of West Tropical Africa
Flora of West Tropical Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2020. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Neotropikey
Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.
http://creativecommons.org/licenses/by/3.0